IMPORTANCE Obesity increases the severe COVID-19 risk. Whether obesity is associated with an increased risk of post-acute sequelae of SARS-Cov-2 infection (PASC) among pediatrics, independent of its impacts on acute infection severity, is unclear. OBJECTIVE To quantify the association between body mass index (BMI) status before SARS-CoV-2 infection and pediatric PASC risk, controlling for acute infection severity. DESIGN Retrospective cohort study occurred from March 2020 to May 2023, with a minimal follow-up of 179 days. SETTING Twenty-six US hospitals. PARTICIPANTS Individuals aged 5-20 years with SARS-CoV-2 infection. EXPOSURES Elevated BMI status assessed before infection. MAIN OUTCOMES AND MEASURES To identify PASC, we first used the ICD-10-CM code specific for post-COVID-19 conditions, and a second approach used clusters of symptoms and conditions that constitute the PASC phenotype. BMI was assessed within 18 months before infection; the measure closest to the index date was selected. Relative risk (RR) for BMI-PASC association was quantified by Poisson regression models, adjusting for sociodemographic, acute COVID severity, and other clinical factors. RESULTS Among the 172136 participants included, the median age of BMI assessment and cohort entry were 12.8 and 13.2 years, 1402 (0.8%) were identified as having PASC with the ICD-10-CM code, and 74317 (43.2%) had more than 1 incident occurrence of PASC symptoms and conditions. Compared with participants with a healthy weight, those who had overweight, obesity, and severe obesity had 4.7% (RR, 1.047; 95% CI, 0.868-1.263), 25.4% (RR, 1.254; 95% CI, 1.064-1.478) and 42.1% (RR, 1.421; 95% CI, 1.253-1.611) higher risk of PASC when identified using the diagnosis code, respectively. The risk for any occurrences of PASC symptoms and conditions also increased in overweight (RR, 1.030; 95% CI, 0.982-1.080), obesity (RR, 1.108; 95% CI, 1.064-1.154), and severe obesity (RR, 1.174; 95% CI, 1.138-1.213), and that for total incident occurrences increased, too, in overweight (RR, 1.053; 95% CI, 1.000-1.109), obesity (RR, 1.137; 95% CI, 1.088-1.188), and severe obesity (RR, 1.182; 95% CI, 1.142-1.223). CONCLUSIONS AND RELEVANCE Elevated BMI was associated with a significantly increased PASC risk in a dose-dependent manner. The biological mechanisms for this association should be investigated in future research.

Dr. Rao received research support from GSK and Biofire and was a consultant for Sequiris. Dr. Chu is an employee of Pfizer. All other authors have indicated they have no conflicts of interest relevant to this manuscript to disclose.

This work was supported in part by the National Institutes of Health (OT2HL161847-01, 1R01LM012607, 1R01AI130460, 1R01AG073435, 1R56AG074604, 1R01LM013519, 1R56AG069880, 1R01AG077820, 1U01TR003709). This work was supported partially through the Patient-Centered Outcomes Research Institute (PCORI) Project Program Awards (ME-2019C3-18315 and ME-2018C3-14899). All statements in this report, including its findings and conclusions, are solely those of the authors and do not necessarily represent the views of the Patient-Centered Outcomes Research Institute (PCORI), its Board of Governors, or the Methodology Committee.

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